Linear combinations and linear independence

Find the proportionality coefficient $k$ between the vectors:

$$\begin{pmatrix} 2.4 \\ -0.6 \\ 1.2 \end{pmatrix} = k \begin{pmatrix} 14.4 \\-3.6 \\ 7.2 \end{pmatrix}$$

Write your answer as a fraction like this: $2/3$. Don't forget to reduce the fraction!